Catalyst and method for selective oxidation



Patented Dec. 15, 1953 t TED STATES CATALYST METHOD FOR OXIDATIGNWilliam R. Middleton, Wenonah, in, .sssighei to socony vacuuin OilCombinilfibdfiinratfid, a corporation of New York No in-sewing.Application Janum:9,1 1951,

SerialNo. -205;231

mins; (Cl. 260-604) '1 .2 The present invention relates to the oxidationI p n no of organic compounds and, more particularly to g L9. MgGEO+QHwselective catalytic conversion of methyl and '1 methylene groups tocarbonyl groups by 's where Ar is an aryl male-s1 substituted oruntaim'ng free oxygen in the presence of a catalyst ,W-mbsfitum; 1

containing at least one oxide or tel'lurlum and a at least one oxide ofrhenium. ,(2) I ,e o a, 4

At the outset it is to be appreciated 'that in C-HMHzOH it'd-C O +'2 theco-p'ending application of Frederick P. Richter for United StatesLetters Patent Serial No.

139,529 filed January 19, 1950 the basic reactions v a l have beendisclosed "and that the present i ven- (b) R CHOHCPWH Te R 000110 +2mo'tion provides an "improvement primarily "of the where uig'thyaiibgndlkvyllw ,yclo'lkyyl, Mm

catalyst disclosed in the -co-p9ndi'ng applicationmet-efwycncandwhermher than hyawghmayy which reference "ben made and'besubs'tituted by any siibstituiitwhich wills'urmethod describedtherein. h v a i e e .4 p

. 1 rive under the reaction =cond1tions, for 'example,

, Q l' mpt m th9 ,d i b d 9th? a phenyl group, a halogen, a. nitro groupand the aforesaid co-pendi-ng application, the present like.

method involves contacting the vapors of anor- N w I 3 ame substancehaving hydrogen atoms 01a g gg b "mgmed that the freging Z methyl ormethylene group activated by the proximity of a double bond; *i. e,alpha to an H 8 H OH unsaturated carbon atom, or a hydroiiy l grouHOEO-; H,o=o-; Ar-; A!E; R'( J; RC; with a gascontaining free oxygeninthe presence i of finely divided catalyst. It is to "be appreciated nthat the phrase 'gas' -'containing free oxyge I ofi includes elementaloxygempure diatomic oxygen,

diatomic oxygen diluted with en mert gas such as nitrogen,helium,-calrbh dioxide-and diatomic (3) compounds containing a sent-erof nnSSZ-toxygen or ozone, and air. uvstieh directly adjacent a methylor methylene Broadly illustrative of the classes of compounds group suchas the double bond of an aryl -'group which may be oxidized in thismanner rand the es en integi al part of an elicyelic fin system;

products obtained are the following equations: (6) m TH SC 3 0' E '35 fTO inc c c V M. .1 7 me he. 'Ie no ;,c'=o

where Z is a :monovalentradical :havingatleast I one center ofuns'aturation'such as 0:0; a group (b) o capable of oxidation to acarbonyl group for .ex- I g: l ample a hydroxyl group; C=" C; (3:0,; orthe v 7 double bond of an aryl group directly adjacent 1H, 0 H?!) (2H1to the methyl or methylene. group and R is hydro- E CH2 Te HQ 7 gen oralkyl or cycloalkyl or aryl or 'alicycli'c or heterocyclic; when R otherthan hydrogen g it can be substituted by any substituentu'which I willsurvive under the reaction conditions, :for v r It i example, a phenylgroup's. halogen, a nitroggroup 2C C and the like.

1 a 1 O e ,=e -11, Te 11 n,

mesa-(mm nczo-tzn+n,o g

TB} H :H. H (b) O It is to be noted that 0 I t. mc=cn-cnm n,o=oH-g-R-+mo .9 Te 7 Te {Q has been "used in the foregoing equations to ino v o lp -=dicate a reaction taking vplace in the presence 1T +150 of a gascontaining free oxygen as defined hereinbefore and a catalyst comprisingat least one oxide of tellurium and at least one oxide of rhenium.

The physical state of the novel catalyst comprising at least one oxideof tellurium and at least one oxide of rhenium apparently isunimportant. For example, it can be used to catalyze the reactionsillustrated hereinbefore as a finely divided mixture of the oxidessuitable for use in continuous operation wherein the catalyst is influidized form. It can be used as a coating on an active or inertsupport and it can be used without support as a larger particle thanthat required for fluid technique.

For the preparation of the novel promoted or mixed catalysts, whethersupported by active or inert materials or unsupported, either of thefollowing procedures can be used.

Procedure A An aqueous solution of perrhenic acid is added to aconcentrated aqueous solution of telluric acid in amount suflicient toprovide about 1 to about 40, preferably about 2 to about 20, mole percent of rhenium oxide based upon the tellurium oxide present in themixture.

When the promoted or mixed catalyst is to be used in the unsupportedform the mixed aqueous solution is exaporated to dryness and the residuemechanically sub-divided. Spray drying or powder metallurgy techniquescan be substituted for the drying and mechanical sub-division whendesired.

When the promoted or mixed catalyst is to be supported, the aqueoussolution of the mixed acids is used to saturate the support which isthen dried.

Procedure B An aqueous solution of perrhenic is prepared and neutralizedcarefully with a basic compound of ammonia, alkali metals or alkalineearth metals, for example, an aqueous solution of sodium hydroxide orpotassium hydroxide, or ammonium hydroxide, calcium hydroxide, calciumcarbonate, magnesium hydroxide or carbonate or the like. The neutralizedperrhenic acid solution is then thoroughly mixed with an aqueoussolution of telluric acid in amount suflicient to provide about 1 toabout 40, preferably about 2 to about 20, mole per cent (based upon thetellurium oxide) of rhenium oxide.

When the promoted or mixed catalyst is to be used unsupported theaqueous solution is evaporated to dryness and the residue mechanicallysub-divided.

When the promoted or mixed catalyst is to be used upon a support theactive or inert support is saturated with the aqueous solution and thendried.

Reference has been made hereinbefore to active and inert supports forthe promoted or mixed catalysts. An active support is one which in theabsence of a tellurium catalyst as described in co-pending applicationSerial No. 139,529 but in the presence of a gas containing free oxygenaccelerates the oxidation of organic substances of the class describedhereinbefore usually to produce oxidation products other than those ofthe carbonyl type illustrated hereinbefore. An organic carbonyl group isa group which exists in that state of oxidation which is intermediatebetween a primary or secondary alcohol and a carboxylic acid. Silica gelis a member of the group of materials'classed as active supports.

An inert support is one which in the absence of a tellurium catalyst asdescribed in co-pending application Serial No. 139,529 but in thepresence of a gas containing free oxygen does not accelerate to anyappreciable extent the oxidation of organic substances of the classdescribed hereinbefore to produce oxidation products. Illustrative ofthe materials classed as inert supports is the fused alumina availableas Tabular Alumina.

In the illustrative but not limiting examples provided hereinafter theconcentration of tellurium (as T802) upon the support is approximately15 grams per cubic centimeters. This is not critical and can be variedwithin the limits set by the concentration of the solutions employed andthe porosity of the support.

EXAMPLE I A gaseous mixture of propylene and air in the proportion ofthe one volume of propylene to three volumes of air was passed throughone volume of promoted or mixed catalyst at the rate of four volumes ofthe gaseous mixture per minute equivalent to a space velocity of four ora propylene space velocity of one. The reaction zone was maintained at atemperature of about 652 to about 653 F. The maximum observedtemperature rise due to the reaction was 4 F. (It has been noted thatthe conversion of one mole per cent of propylene to acrolein results ina rise of about 1 F.)

The catalyst employed in this run was prepared by the method ofProcedure B given hereinbefore and contained 0.05 mole of NaReOr, orequivalent oxides, per mole of tellurium oxide. In other words, theconcentration of rhenium oxide was about 5 mole per cent based upon thetellurium.

The gaseous product of the conversion was absorbed in water at atemperature of about 40 F.

-It is to be noted that although the observed rise in temperature due tothe reaction was only about 4 F. nevertheless about 9.5 per cent of thepropylene was converted to acrolein.

EXAMPLE H A gaseous mixture of propylene and air in the proportion ofone volume of propylene to three volumes of air was passed atessentially atmospheric pressure through about 0.82 volumes of catalystat a rate of about four volumes of gaseous mixture per minute or a spacevelocity of 4.88 equivalent to a propylene space velocity of 1.22. Thetemperature of the reaction zone was maintained at about 651-656 F. Themaximum observed temperature rise in the catalyst due to the reactionwas 7 F.

The catalyst was prepared in accordance with the method given inProcedure A (hereinbefore) and contained 0.05 mole of ReOX per mole oftellurium oxide, i. e., 5 mole per cent ReOx.

The gaseous product was absorbed in water at a temperature of about 40F. Analysis of the solution so obtained indicated that about 10.3 percent of the propylene was converted to acrolein.

EXAMPLE III A gaseous mixture of propylene and air in the proportion ofone volume of propylene to three volumes of air was passed atessentially atmospheric pressure through one volume of catalyst at aspace velocity of four (propylene space velocity 1). The temperature ofthe reaction zone was maintained at about 702-703 F. The

maximum observed. rise in temperature in the catalyst. bed: due to thereaction was 3 F.

The catalyst was. prepared by the method described under Procedure A-supra except that no perrh'enic. acid: or other promoter material wasadded. In other words, the catalyst comprised predominantly at least oneoxide of tellurium as defined in co-pending application Serial No.139,529. Consequently, the results of this run establish a. norm withwhich other results can be compared.

The: gaseous product was absorbed in water at a temperature of about 40F. Analysis of the aqueous solution so obtained indicated that about 2.1per cent of the propylene was converted to acrolein although thereaction: temperature employed was about 50 F. higher.

The foregoing indicates that with rhenium promoted tellurium catalystsreaction temperatures of the order of about 50 F. below those requiredwhen employing, the unpromoted catalysts described in co -pendingapplication Serial No; 139,529 can be used and increased: conversionsobtained. Accordingly, the present invention provides a means for.convertingorganic sub:- stances of the class described. to carbonyls attemperatures of about 600- to about 700 F.

In a manner similar to that illustrated hereinbefore a mixture of.refinery gases, such as a propylene-propane fraction containing, forexample, about 50 mole per cent propylene and about 45 mole per centpropane can: be treated to obtain acrolein. Toluene can be selectivelyoxidized. to benzaldehyde and isobutylenecan be selectively oxidizedto-methacroleint Broadly; as disclosed in co-pend'ing application SerialNo. 139,529, compounds having at least one methyl: or methylene groupdirectly adjacent toa center of unsaturation or directly adjacent to a.hydroxyl group can be oxidized to the. corresponding compounds in whichthe methyl or methylene group is present as an aldehyde or ketonic groupby gas containing free oxygen in the-presenceofa catalyst com prisingabout 1.to about 40; preferably about 2 tc about 20' mole percentofrhenium oxide and the balance predominantly at least one oxide oftel- I'urium.

The organic substance to oxidizing gas ratio can be varied over a widerange: although it is preferred to use ratios of about 1:1 to about 1:9.

Broadly defined, the substances which can be oxidized. with. air orother gas containing .fi'ee oxygen in the presence of non-stoichiometricquantities of finely divided catalyst comprising predominantly at leastone oxide of tellurium, are those having hydrogen atoms attached to acarbon atom alpha toan unsaturated carbon atom such asv in. olefins ofthree or more carbon atoms; isolated diolefins; i; e;, diolefins inwhich there is at least one methylene or substituted methylene groupbetween the: 'olefinic carbons; acetylenic hydrocarbons having at leastthree carbon atoms; conjugated. diolefins of more'than four carbonatoms; cy'c'l'oolefi'ns, for example, cyclopentadiene; aromatichydrocarbons, such as xylene, methyl naphthalenes, methyl anthracenesand the like, or alpha to a hydroxyl group, such as ethanol, propanol,pentanol, isopentanol, octanol, octadecanol, octadecenol, ethandiol,propandiol, butylene glycol, pentylene glycol, octandiol and in generalhydrocarbons, substituted hydrocarbons and primary and secondaryalcohols of up to 22 carbon atoms. For example, paraffin wax (18-24carbon atoms) can be halogenated, de-

wherein R and R are alkyl or aryl groups substitutedor unsubstituted canbe oxidized in the manner described. hereinbefor e and converted to thecorresponding carbonyl compounds.

Thus, for example, 1=,3-butadiene, '1,3- pentadiene(alphamethylbutadiene)1,4 pentadiene; 2- methyl-LB-buta-diene(isoprene), LS-hexadiene (diallyl), 2,3dimethyl-1,3-butadiene(diisopropenyl ,3 methyl-LB-hexadienc 3-methyl-2,4-hexadiene;2,7-heptadiene, 4-methyl--1,6-heptadiene, 2,5-dimethyl-2,4 -hexadiene,3-methyl- 1,5-octadiene, 1,4-nonadiene, 3-,7-decadieneca-n be oxidizedwith air in'the. presence of finely divided catalyst'com prisingpredominantly at least one oxide of: tellurium at temperatures of about350 to about 550 C. or generally at temperatures at which the diolefinis gaseous but below the cracking temperature of the diclefin tothecorresponding carbonyl compounds.

Illustrative of another group of hydrocarbons which can be oxidized tothe corresponding carbonyl compounds in gaseous phase with pure ordiluted gaseous oxygen in the presence of the tellurium catalyst attemperatures at which the hydrocarbon is gaseous but below the crackingtemperature of the hydrocarbon are the following members of. theacetylene series: 2-butyne, 2-pentyne, z-hexyne, 3-hexyne,.4-methyl-2-pentyne, 3-heptyne,5-methyl-2-hexyne, 4,4-dimethyT-2pentyne', fi methyld-ethyl- 3-heptyne, 2- undecyne, 6'-dodecyne,2-hexadecyne, 9'-octade"- cyne.

Illustrative of the aromatic'hydro'carbons which be oxidized to' thecorresponding carbonyl com-pounds by air in the presence of the tellurium catalyst at temperatures between the normal-boilingpoint of thehydrocarbon and the cracking temperature thereof are tri'methylbenzene,o-ethyltoluene (I-methyl-2 ethylbenzene)' l-methy-l z-prop'ylbenzene,1,311'1l11l8thY1Ef-8fh ylbenz'ene; tetramethylbenzehe;1--methy1--4isobutylbe'nzene, 1 ,2-dimethyli propylbenzene; 1,-2-,4-trimethyl-5-ethylbenzene; l-methyl-fi-amylbenzene,1,3-dimethyl-4,6-diethylbenzene; 1=--methyl-2-propyl-4-isopropylbenzene, l,3-',5-trimethyl-2;4diethylbenzene, alpha and beta styrene,l-phenyl-LS-buta'diene, I-methyl-i propenylben'zene, l-phenyl-2-pentene,dimethyl naphthalene, dimethylanthracene, dimet'hylphe nanthrenei andthe like.

Illustrative of the cyclo-oleflns which can be oxidized to thecorresponding carbonyl compounds by air. in the presence of thetellurium" catalyst at temperatures between theboiling point and thecracking temperature of the cycloolefin 2-methyl-1-,4-pentadiene(isodiallyl);

compound and the temperature at which said compound cracks or decomposesare the following: glycol, propandiol-1,2; propandiol-1,3; 1,2-dihydroxybutane, 1,4-dihydroxybutane,2,3-dihydroxyhexane and the like.Monohydroxy compounds such as the aliphatic alcohols, ethanol, butanol,propanol, hexanol, octanol and the like can also be oxidized to thecorresponding carbony1 compounds 'by gaseous oxygen in the presence ofthe tellurium catalyst at temperatures between the boiling point of thealcohol and the temperature at which the alcohol decomposes.

A characteristic of the catalyst disclosed hereinbefore is its capacityto promote the oxidation of methyl or methylene groups directly adjacentto a center of unsaturation in an organic compound such as, for example,the unsaturation found in aromatic compounds, olefins or carbonylgroups. A further distinguishing feature is the fact that although thecatalyst catalyzes the oxidation of such methyl and methylene groups tocarbonyl groups, =C-O or o JLE it does not catalyze the oxidation ofcarbonyl groups to higher states of oxidation. Thus, it is specific forthe following transformations:

Compounds intermediate between the above reactants and the products inoxidation state such as, for example, benzyl alcohol, allyl alcohol andthe like also can be oxidized using the technique disclosedhereinbefore. Ethylene can be oxidized to glyoxal and anthracene toanthraquinone as can organic substances which form in situ reactantssuch as those the oxidation of which has been discussed herein or theirintermediate oxidation products through dehydrogenation, dehydration,rearrangement, dehalogenation, dehydrohalogenation and similarreactions, for instance, methyl cyclohexadiene, tertiary butanol,

beta-pinene, 2,3-diiodopropane and alphabromodiethylketone.

Iclaim:

1. In the method of converting propylene to acrolein which comprisespassing refinery gases containing propylene mixed with gas containingfree oxygen through a catalyst consisting predominantly of an oxide oftellurium, the improvement which comprises employing a catalystcontaining about 1 to about 40 mole per cent of an oxide of rhenium andthe balance consisting predominantly of an oxide of tellurium.

2. The method of converting propylene to acrolein as described and setforth in claim 1 wherein the catalyst contains about 2 to about 20 moleper cent of an oxide of rhenium and the balance consists predominantlyof an oxide of tellurium.

3. In the method of converting activated groups selected from methyl andmethylene groups to carbonyl groups which comprises passing an organicsubstance having an activated radical selected from the group consistingof methyl and methylene radicals mixed with a gas containing free oxygenthrough a catalyst consisting predominantly of an oxide of tellurium,the improvement which comprises employing a catalyst consistingessentially of about 1 to about 40 mole per cent of an oxide of rheniumand the balance consisting predominantly of an oxide of tellurium.

4. The invention as described and set forth in claim 3 wherein thecatalyst contains about 2 to about 20 mole per cent of an oxide ofrhenium and the balance consists predominantly of an oxide of tellurium.

5. In the method of converting an activated group selected from a methyland methylene radical to a carbonyl radical which comprises passing agaseous mixture comprising gas containing free oxygen and a compoundhaving a composition corresponding to the formula Z-CH2R through acatalyst consisting essentially of an oxide of tellurium, said compoundZCH2R being a compound in which Z is a monovalent radical having anactivating group selected from the group consisting of olefinic C C,CEC, C=O, OH, and

aromatic C C, and R is selected from the group consisting of hydrogen,alkyl, cycloalkyl, aryl and heterocyclic, the improvement whichcomprises employing a catalyst consisting essentially of about 1 toabout 40 mole per cent of an oxide of rhenium and the balance consistingpredominantly of an oxide of tellurium.

6. The invention as set forth and described in claim 5 wherein thecatalyst consists essentially of about 2 to about 20 mole per cent of anoxide of rhenium and the balance consists predominantly of an oxide oftellurium.

7. A novel catalyst consisting essentially of about 1 to about 40 moleper cent of an oxide of rhenium and the balance consisting predominantlyof an oxide of tellurium.

8. A novel catalyst consisting essentially of about 2 to about 20 moleper cent of an oxide of rhenium and the balance consisting predominantlyof an oxide of tellurium.

WILLIAM R. MIDDLETON.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,103,017 Ellis July 7, 1914 2,227,672 Pier et a1. Jan. 7,1941 2,383,711 Clark et al Aug. 28, 1945 2,451,485 I-Iearne et a1. Oct.19, 1948 2,530,923 Turk Nov. 21, 1950 FOREIGN PATENTS Number CountryDate 13,297 Great Britain 1915 625,330 Great Britain 1946

1. IN THE METHOD OF CONVERTING PROPYLENE TO ACROLEIN WHICH COMPRISESPASSING FIBERY GASES CONTAINING PROPYLENE MIXED WITH GAS CONTAINING FREEOXYGEN THROUGH A CATALYST CONSISTING PREDOMINANTLY OF AN OXIDE OFTALLURIUM, THE IMPROVEMENT WHICH COMPRISES EMPLOYING A CATALYSTCONTAINING ABOUT 1 TO ABOUT 40 MOLE PER CENT OF AN OXIDE OF RHENIUM ANDTHE BALANCE CONSISTING OF PREDOMINANTLY OF AN OXIDE OF TELLURIUM.